Now, let's start today's lesson.

现在咱们开始讲课。

What we are going to cover today is…

我们今天要讲的内容是······

First of all, I would like to talk about…

首先，我想讲一下······

Today, I am going to talk about…/What I want to do today is…

今天我要讲的内容是/我今天要做的事情是·····

The important point I want to make today is…

我今天要讲的重要知识点是······

Today's topic is…

今天的话题是······